Conventionally lateral transistors with an emitter area and a collector area formed on the same principal surface are constructed so that the emitter-terminal covers the major part on a base area between the emitter area and the collector area by way of an insulation protective film as disclosed, for example, in Japanese Utility Model Publication No. 21934/1971. The structure is intended to minimize a recombination on the surface of base area of a carrier poured from the emitter to the base area by the emitter-terminal covering the major part on said base area.
In case, however, an element is manufactured practically in the structure as described above, the collector area must be widened or enlarged so as to keep the collector-terminal connected to said collector area and the emitter-terminal covering the major part on said base area from coming in contact each other. The lateral transistor cannot, therefore, be minimized in size due to this enlargement of the collector area as described, and an integration density cannot be made large particularly in such case where it is manufactured on the same substrate as other semiconductor element. Thus a big shortcoming is unavoidable with the lateral transistor proposed by said aforementioned Japanese Utility Model Publication.